Process for producing vitamin A

ABSTRACT

A process for producing vitamin A esters, vitamin A aldehyde and vitamin A acid esters from esters of 3,7-dimethyl-9-(1-hydroxy2,2,6-trimethylcyclohexyl)-nona-2,4,6-trien-8-yn-1 -ol and 3,7dimethyl-9-(1-hydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4,6trien-8-ynoic acid including intermediates in this process.

United States Patent [191 Olson et a1.

[ PRocuss FOR PRODUCING VITAMIN A [75] Inventors: Gary Lee Olson, Westfield; Gabriel Saucy, Essex Fells, both of NJ.

73 Assignee: HoffInann-La Roche Inc., Nutley,

[22] Filed: Apr. 26, 1974 [21] Appl. No.: 464,398

Related US. Application Data [63] Continuation-impart of Ser No. 303,162, Nov. 2,

1972, abandoned.

[52] US. Cl 260/4l0.9 V; 260/410; 260/617 A; 260/488 A; 260/476 R [51] Int. Cl. CllC 3/02 [58] Fieldvoi Search"... 260/410.9 V, 410.9 R, 410, 260/617 A, 488 A, 476 R; 252/431 R [56] References Cited UNITED STATES PATENTS 2,579,658 12/1961 Evans 260/617A 7 Dec. 23, 1975 2,705,728 4/1955 lniloffen 260/617 A 2,775,626 12/1956 Schaaf 260/617 A 3,006,939 10/1961 Pommer 260/410 RV v FOREIGN PATENTS OR APPLICATIONS 696,235 12/1951 United Kingdom 260/617 A 624,486 6/1949 United Kingdom..... 260/617 A 605,772 6/1948 United Kingdom 260/617 A Primary ExaminerWinston A. Douglas Assistant Examiner- John F. Niebling Attorney. Agent. or Firm-Samuel L. Welt; Jon S.

Saxe; Willaim l-isEpstein 15 Claims, N0 Drawings l PROCESS FOR-PRODUCING VITAMIN A CROSS REFERENCE To'RELATED' I APPLICATIONS, This application is a continuation-in-part application of US. Pat. No. Application Ser.No.' 303,162; filed Nov. 2, 1972 now abandoned Olson and Saucy.

SUMMARY OF THE INVENTION In accordance with this invention, vitamin A esters and vitamin A acid ester type compounds which have the formula:

wherein R is -cH oH, cno, CI-I OR or R, is alkanoyl or aroyl; and R is alkyl, aryl or aral- 3O y can be prepared from compounds of thefonnula:

wherein R 'is as above; and compounds of the formula:

wherein R is as above. I

process provides a method for synthetically producmg all trans vitamin A compounds of the formula I from the compounds 'of formulae II or III irrespective of v the cis/trans configuration about the double bonds in the compounds of formulae II and III.

DETAILED DESCRIPTION OF THE INVENTION The numbering of the carbon atoms in the various formulae set forth throughout this application is given for the purpose of convenience only.

The term halogen includes all four halogens, i.e., iodine, bromine, chlorine and fluorine, with bromine and chlorine being preferred. The term lower alkyl as used throughout this application comprehends both straight and branched chain hydrocarbon groups containing from 1 to 6 carbon atoms such as methyl, ethyl, propyl and isopropyl. The term alkyl includes lower alkyl containing from l to 8 carbon atoms as well as higher alkyl groups which contain from 7 to 18 carbon atoms such as decyl, hexadecyl, octadecyl, octyl, nonyl, dodecyl, etc. The term lower alkoxy as used throughout this application comprehends lower alkoxy groups containing from 1 to 6 carbon atoms such as methoxy, propoxy, 'ethoxy, etc., preferably methoxy or ethoxy.

.The tenn cycloalkyl comprehends cycloaliphatic groups having a ring of from 3 to 7 carbon atoms such as cyclopropyl, cyclopentyl and cyclohexyl, which can be unsubstituted or substituted in one or vmore positions with a lower alkyl group. The cyclo alkyl groups can contain from 3 to 15 carbon atoms.

The term aryl as used throughout this application includes mono-nuclear aryl groups such as phenyl which can be substituted or unsubstituted in one or more positions with lower alkyl, or an electron withdrawing group such as carboxy, formyl, trifluoromethyl, alkanoyl, phenyl, alkoxycarbonyl, halogen, nitro, or polynuclear aryl groups such as naphtyl, anthryl, phenanthryl, azulyl, etc., which may be substituted with one or more of the aforementioned groups. The

III

preferred aryl radical is phenyl, or phenyl substituted with lower alkyl, nitro, cyano, trifluoromethyl, or halogen.

The term aralkyl denoted aryl lower alkyl groups 60 wherein-aryl and lower aklyl are defined as above. The

preferred aralkyl groups is benzyl. The term aroyl denotes the group wherein aryl is defined as above. The preferred aroyl group is benzoyl.

The term alkanoyl includes lower alkanoyl groups containing from 2 to 6 carbon atoms such as acetyl,

propionyl, butyryl, etc., as well as higher alkanoyl groups containing from 7 to 18 carbon atoms such as palmitoyl, pentadecanoyl, octadecanoyl, octanoyl, decanoyl, etc.

wherein -OR is OI-l or a leaving group or aroyl; and R is as above; and R, is hydrogen, alkanoyl or aroyl.

The compound of formula II is converted to the com- In accordance with this invention, the compound of 5 pound of formula IV, via step (a), by heating the comformula II can be converted to a vitamin A compound of the formula:

H3 Ha CH2 0R1 wherein R is as above; by the following reaction scheme:

(m H3 en OR l 13\ l 2 l CH3 CH3 )VCH 0R l H CHZORl pound of formula II in an inert organic solvent in the presence. of an organo-silicon vanadate of the formula:

wherein R is alkyl, cycloalkyl, aryl, aryl lower alkyl, or cycloalkyl substituted lower alkyl; R; is R, or:

m is an interger from 1 to 3; and n is an interger of from 0 to 2; with the proviso that the sum of m and n is 3.

Among the preferred organo silicon vanadate catalysts of this invention are catalysts of the formula:

wherein R is phenyl of phenyl substituted in one or more positions with an electron withdrawing group;

R is lower alkyl, cycloalkyl, phenyl, or phenyl lower alkyl;

wherein R' is phenyl substituted'in one or more positions with an electron withdrawing group; R., is lower alkyl, cycloalkyl, phenyl or phenyl lower alkyl; and m and n are as above;

Where R or R is phenyl substituted in one or more positions with an electron withdrawing group, any conventional electron withdrawing group can be utilized. Among the preferred electron withdrawing groups are those disclosed on page 65 l of Fieser and Fieser, Textbook of Organic Chemistry, 1954 Edition. These groups are:

-COOI-I Also included among the preferred electron withdrawing groups are -F, CF and C6H5. Among the organo silicon vanadate catalysts which are preferred are. the compounds where R, is lower alkyl (particularly methyl, ethyl, isopropyl or n-butyl),

naphthyl, phenyl (particularly phenyl), lower alkyl.

substituted phenyl (particularly tolyl or xylyl), nitro substituted phenyl (particularlry m-nitrophenyl or 3,5-

dinitrophenyl); halogen substituted phenyl (particuformed in the reaction with the aid of an entraining agent such as, for example, benzene;

ii. the reaction of, for example, vanadium oxytrichloride with, for example, a trialkyl silanol or triaryl silanol in the presence of a base such as pyridine or ammonia;

iii. the reaction of, for example, vanadium oxytrichloride with, for example, a trialkyl alkali silanolate of the formula [alkyl] SiOMe(I) or a triaryl alkali silanolate of the formula [aryl] SiOMe( I); where Me is an alkali metal;

iv. the reaction of, for example, a vanadium acid ester of the formula [alkoxy] -V=O with, for example, a trialkyl silanol or triaryl silanol, if desired in the presence of catalytic amounts of an alkylor aryl alkali silanolate (e.g., a trialkyl alkali silanolate);

v. the reaction of, for example, silver orthovanadate of the formula Ag VO with for example, a trialkyl silyl halide to the formula [alkylhSiCl or a triaryl silyl halide of the formula [aryl] SiCl in a solvent such as, for example, benzene or methylene chloride;

vi. the reaction of, for example, vanadium pentoxide with, for example, a hexaalkyl disiloxane of the formula [alkyl] SiOSi[alkyl] at an elevated temperature, for example, at about C.; and

vii. the double reaction of a vanadium acid ester of the formula [alkoxy]3-V=O with a silyl ester of the formula (R Si-O-CO R" where R" is lower alkyl, where R, is as above, for example, with tripropyl orthovanadate with the expulsion of propyl acetate peferably in a solvent, such as n-heptane, with which the ester provided in the reaction forms an azeotrope that can be separated from the reaction medium.

The reaction step of (a) is carried out in an inert organic solvent. In carrying out this reaction, any conventional inert organic highboiling solvents can be utilized, i.e., solvents boiling above 35C. Among the preferred solvents are included aliphatic hydrocarbons, particularly cyclododecane, decalin, paraffin and paraffin oil; aromatic hydrocarbons, particularly toluene and xylene; ethers, particularly anisole and dioxane.

In carrying out the reaction of step (a) temperatures of 35C. or above are utilized. The reaction is expeditiously carried out at a temperature of from 60 to 200C., with a temperature of about 80 to C. being generally utilized. Generally, it is preferred to carry out this reaction at the reflux temperature. If

,desired, the reaction can also be carried out under pressure, in which case pressures up to about 50 atmospheres can be used. In the case where pressure is utilized, low boiling solvents which include lower aliphatic and aromatic hydrocarbons such as benzene, heptane and cyclohexane can be used.

In some cases in the reaction of step (a), a compound of the formula:

wherein R, is as above;

is formed in admixture with the compound of formula IV. The yield of the compound of formula IV in this mixture can be increased by heating the compound of formula IV-A to the reflux temperature of the reaction medium for a period of at least 30 minutes to convert the compound of formula IV-A to the compound of formula IV. If desired, heating times of 20 hours or longer can be utilized. However, since such long heating times do not increase the yields of the compound of Formula IV, the use of long heating times is not economic.

On the other hand, the mixture containing the compound of formula IV and formula IV-A can be converted via steps (b), (c) and (d) to the compound of formula I-A with the compound of formula IV-A being transformed into the following intermediates:

and

wherein R is as above.

In accordance with another preferred embodiment of 50 this invention, the reaction of step (a) is carried out utilizing an organo silicon vanadate catalyst described I hereinbefore and in the presence of a. si1ano1 of the formula:

(R )SiOI-I wherein R'., is alkyl, aryl, cycloalkyl, aryl lower alkyl, 'cycloalkylsubstituted lower alkyl. The silanol can be present in the reaction medium in an amount of at least 0.01 mole of the compound of formula II above. On the other hand, the silanol can be utilized as the solvent medium. Generally, it is pre- 9-trans, 1 l-trans, 13-trans;

9-cis, ll-trans, 13-trans;

9-trans, ll-trans, l3-cis;

9-trans, ll-cis, l3-cis;

9-cis, ll-cis, 13-trans;

9-cis, 11-cis, 13-cis;

9-trans, ll-cis, l3-trans; and

9-cis, ll-trans, l3-cis; or as mixtures of the above isomers.

.The reaction of step (a) does not substantially change the geometrical configuration of the double bonds in the compound of formula 11. Therefore, the compound of formula IV has substantially the same geometrical configuration as the compound of formula II. If the compound. of the formula II is a mixture of geometric isomers or is other than the 9-trans, 1 l-trans, 13-trans isomer, the compound of formula IV can be isomerized to produce the all trans isomeric form of the compound of the formula IV. This reaction can be VI-A carried out by treating the compound of formula IV with an organic acid or an organic amine base at temperatures of from 20 to 160C. In carrying out this isomerization reaction, any organic acids which include aroic acids such as benzoic acid or (lower alkanoic acids, such as acetic acid can be utilized. Among the preferred lower alkanoic acids for use in isomerizing the compound of formula IV are included acetic acid, propionic acid, etc. On the other hand, this reaction can be carried out by utilizing an organic base such as a tertiary organic amine base or'a quaternary amine 0 base. Among the preferred organic amine bases are ferred to utilize the silanol in the amount of from 5 to 65 mole based upon the moles of the compound of formula II above.

The compound of formula II can exist in various isomeric forms due to the double bond at the 9-10, 11-12 and 13-14 positions. Therefore, the compound of formula II can exist in the following stereoisomeric forms:

included pyridine, piperidine acetate, triethylamine, trimethylamine, diazabicyclo-[2,2,2]-octane, methylammonium acetate, etc. In carrying out this reaction, no solvents need be present since the organic' 5 acid or the organic amine base can be utilized as the solvent medium. On the other hand, any conventional inert organic solvent can be added to the reaction mixture, if desired. Among the solvents which may, if de-, sired, be added to the reaction mixtures are included,

the aromatic solvents such as benzene, toluene, etc., or

tetrathe solvents hereinbefore mentioned. Among the preferred solvents for use in this reaction are the aromatic solvents such as benzene as well as the other solvents mentioned hereinbefore.

A compound of the formula IV is converted to the compound of formula V by reducing the compound of formula IV. Any conventional method for reducing ketones to alcohols can be used to carry out this method. A method of carrying out the reaction of step (b) is by the use of reducing agents. Any reducing agent conventionally utilized for converting ketones to alcohols can be used to carry out the reaction of step (b). Among the preferred reducing agents are the complex metal hydrides. Any conventional complex metal hydride reducing agent could be utilized in carrying out this reaction. Among the complex metal hydrides there can be used, for example, an alkali metal borohydride such as sodium borohydride or lithium borohydride, alkaline earth metal borohydrides such as calcium borohydride and alkali metal aluminum hydrides such as lithium aluminum hydride or diisobutyl aluminum hydride, preferably sodium dihydro-bis(2-methoxyethoxy) aluminum. This reduction is carried out in an inert organic solvent medium. Any conventional inert organic solvent can be utilized in carrying out this reaction. Among the preferred inert organic solvents are included, tetrahydrofuran, dioxane, diethyl, ether, hexane, toluene, benzene or xylene. In carrying out this reduction reaction, temperature and pressure are not critical and this reaction can be carried out at room temperature and atmospheric pressure. On the other -OR are alkylsulfonyloxy such as methylsulfonyloxy, arylsulfonyloxy such as p-toluenesulfonyloxy, alkanoyloxy or aroyloxy such as benzyloxy. Any conventional method of converting a hydroxy group to a leaving group can be utilized in the formation of the compound of formula VI.

Where R in the compound of formula V is hydrogen, the compound of formula V maybe treated with an acylating agent such as a lower alkanoylating or aroylating agent. In general, this reaction is carried out be treating the compound of formula V with an organic acid anhydride or a functional derivative of an organic acid. The preferred organic acids are lower alkanoic acids, particularly acetic acid and benzoic acid. Any of r the conditions conventional in esterifying hydroxy groups can be utilized in converting the compound of formula V where R, is hydrogen to the compound of formula VI. If one mole of the acylating agents is utilized per mole of the compound of formula V where R," is hydrogen, the hydroxy group at the l5-position. a.

is esterified. On the other hand, if two or more moles of the acylating agent are utilized per mole of the compound of formula V, both the hydroxy groups at the 8 i and positions canbe esterified.

hand, elevated or reduced temperatures can be uti- The compound of formula V can, in accordance with one embodiment of the invention, be converted to the compound of formula VI by converting the hydroxy group on position 8 or the compound of formula V to a leaving group. This can be accomplished where R," in the compound of formula V is alkanoyl or aroyl. Any

conventional'le aving group can be utilized in this procedure. Among the preferred leaving groups formed by The compound of formula VI is converted to the compound of formula LA by treating the compound of formula VI with a dehydrating agent. In carrying out this reaction, any conventional dehydrating agent can be utilized. Among the preferred dehydrating agents are included thionyl chloride, phosphorous oxy-chloride; inorganic acids such as sulfuric acid, hydrogen bromide, hydrogen chloride, etc.; strong organic acids such as p-toluene sulfonic acid; alkyl sulfonic acids suchas methane sulfonic acid. Generally, this reaction is carried out in an inert organic solvent. Any conventional inert organic solvent can be utilized in carrying out this reaction. Among the preferred inert organic solvents whenthionyl chloride and phosphorous oxychloride are utilized, is pyridine. On the other hand, when hydrogen bromide is utilized, methylene chloride or chloroform are the preferred solvents. The dehydration produces a trans configuration about the 7-8 double bond in thecompound of formula l-A.

If desired, the vitamin A ester of formula I-A can be converted to the corresponding alcohol by conventional hydrolysis or reduction procedures well known in the art. 7

The compoundof formula III can be converted to a vitamin A acid ester of the formula:

CH CH wherein ,R, is as above; by the following reaction scheme:

CH CH wherein R is and OR are as above.

The compound of formula III is converted to the compound of formula VII, via reaction step (e), by heating the compound of formula III in the presence of an organo-silicon vanadate catalyst described in connection with step (a). The reaction of step (e) is carried out utilizing the same reaction conditions described in connection with the reaction of step (a). The preferred method for carrying out this reaction step is to utilize the aforementioned organo-silicon vanadate catalyst in the presence of a silanol such as described in reaction CH3 CH3 H step (a). In the reaction of step (e), a compound of the Vll C H I C OR.I x

formula:

CH CH VII-A wherein R, is as above;

can be formed in admixture with the compound of formula VII. The yield of the compound of formula VII in this mixture can be increased in the same manner as described in connection with reaction step (a). On the other hand, a mixture containing the compound of formulae VII and VII-A can be converted via reaction steps (f), (g) and (h) to the compound of formula 1-8 with the compound of formula VII-A being converted to the following intermediates:

wherein R is as above; and

VIII-A This isomerization is carried out in the same manner 20 described in connection with the isomerization of the compound of formula IV. The compound of the formula VII can be converted to a compound of the formula VIII by reducing the compound of the formula VII, as in step (b), by catalytic hydrogenation or preferably with sodium borohydride. Reduction with sodium borohydride is carried out in the same manner as described in connection with step (b). When sodium borohydride is utilized, only the keto groups at the 8 position of the compound of formula VII is reduced. 30

The ester linkage IX-A is not effected by this reduction. The compound of the formula VIII may be converted, if desired, to the compound of the formula IX via reaction step (g) by converting the free hydroxy group to a leaving group. The same techniques, leaving groups and conditions described in connection with reaction step (c) can be utilized in carrying out this conversion. The compound of formula IX, either containing a free hydroxy group or with a leaving group substituted thereon, is converterd to the compound of formula I-B by treating the compound of formula IX with a dehydrating agent in the same manner described in connection with reaction step (d). This reaction produces a trans configuration across the double bond at the 7-8 positions on the compound of the formula I-B.

The compound of formula II can exist in an isomeric form where there is a cis configuration across the 9-10 double bond and a trans configuration across the 1 1-12 double bond. This compound can be prepared via the following reaction scheme:

wherein R is as above; Y is lithium, sodium or MgX; and X is chlorine, bromine or iodine; A represents a cis configuration; and A represents a trans configuration. The compound of formula X is reacted wtih the compound of formula XI via a Grignard' reaction to produce the compound of formula XII. In carrying out this reaction, any of the conditions which are conventional for carrying out Grignard reactions can be utilized. Generally, this reaction is carried out in an inert organic solvent medium. Among the preferred solvents are diethyl ether and tetrahydrofuran. In carrying out this reaction temperature and pressure are not critical and this reaction can becarried out at room temperature and atmospheric pressure. On the other hand, elevated temperatures and pressures can be utilized. Generally, it is preferred to carry out this reaction at a temperature range of from to 40C. Conveniently, moisture is excluded and the reaction is carried out in an atmosphere of a protecting gas, preferably nitrogen. In carrying out the reaction of step (j), the compound of formula XII is converted to its salt form, Le, a compound of the formula:

wherein Y is as above.

The commpond of formula XII-B is reacted with a compound of formula XIII under conditions conventional for Grignard reactions to form a compound of the formula XIV. This reaction is carried out in the same manner as described in connection with step (i) with a mixture of diethyl ether and benzene being the preferred solvent.

The compound of formula XIV is converted to the compound of formula II-B via step (k), by treating the compound of formula XIV with an alkanoic acid or an aroic acid. Any conventional alkanoic acid containing from 2-18 carbon atoms can be utilized to carry out 65 this reaction. Among the preferred alkanoic acids which can be utilized to carry out this reaction are included acetic acid, propionic acid, palmitic acid, pentadecanoic acid, octadecanoic acid, decanoic acid,

etc. Any conventional aroic acid can be utilized to carry out this reaction. Among the preferred aroic acids are benzoic acid, phthalic acid, p-phenylazobenoiz acid. In carrying out this reaction, the lower alkanoic or arobic acid can act as the solvent medium. On the other hand, this reaction, can, if desired, be carried out in an inertorganic solvent medium. Any conventional inert organic solvent can be utilized as the reaction medium. Among the preferred solvents which can be utilized are included benzene, toluene, as well as the solvents hereinbefore mentioned. In carrying out this reaction, temperature and pressure are not critical and this reaction can be carried out at room temperature and atmospheric pressure. On the otherhand, if desired, elevated temperatures and pressures can be utilized. Temperatures as high as the reflux temperatures of the reaction medium can be utilized in carrying out the reaction of step (k). i

The stereo configuration of the double bond at the 1 1-12 and 13-14 positions in the compound of formula II-B does not depend upon the configuration of the double bond at the 3-4 position in the compound of formula XI. The configuration of the double bond at the 3-4 position in the compound of formula XI is unchanged by the reaction of step (i) such that the compound of formula XII has the same configuration about the 3-4 double bond as in the compound of formula XI. The same is true for the reaction of step (i), the configuration of the double bond in the 3-4 position of the compound of formula XII is the same as the configuration of the 12-13 double bond in the compound of formula XIV.

The reaction of step (k) produced of formula II-B having exclusively the 9-cis, l l-trans configuration about the double bonds, regardless of whether the l2-l3 double bond in the compound of formula XIV (or the 3-4 double bond in the compound of formulae XII and XI) are cis, trans, or a mixture of cis and trans.

The compound of formula II can also be prepared from a compound of the formula:

This reaction is carried out by treating the compound of formula XV with an alkanoic or aroic acid in the same manner as described in connection with reaction step (k). This reaction does not effect the sterochemistry across the double bonds in the compound of formula XI.

The compound of formula XV is prepared from a compound of formula:

XVI

In preparing a compound of formula XV, the com- 10 The compound of formula III is converted to the pound of formula XVI is reacted via a Grignard reaction with CI-I =CI-IY wherein Y is MgX or lithium; and X is as above. Depending upon the geometrical configuration of the starting material of the formula XVI, a compound of formula II having various geometrical configurations about the double bonds can be produced. This reaction is carried out in the same manner as described in connection with reaction step (h). The preferred solvent in this reaction is a mixture of benzene and diethyl ether.

Where the compound of formula II is any isomeric form, or is a mixture of isomers, this compound can be prepared from the compound of formula III via an intermediate of the formula:

(XI ll) compound of fonnula XVII by reduction with lithiumaluminum hydride, lithium borohydride, diisobutylaluminum hydride and sodium dihydro-bis( 2- methoxyethoxy)aluminum in the same manner as de- 15 scribed in reaction step (h). The compound of formula XVII is converted to the formula II by conventional .esterification procedures utilizing an alkanoylating or aroylating agent such as described in connection with the conversion of compounds of the formula V to com- 20 pounds of the formula VI via reaction step (c). However, reactive derivatives of alkanoic acids containing from 2 to 18 carbon atoms can be utilized as the alkanoylating agent.

The compound of the formula II] can be prepared in 25 its various isomeric forms or as amixture of isomers by the following reaction scheme:

. XVII ,(xxl l) (Ill) wherein R, and Y are as above.-

The compound of formula XII is reacted with the compound of formula XX to produce a compound of formula XXI via reaction step (I). This reaction is carried out via a Grignard reaction utilizing the same conditions described in connection with reaction step (i). The preferred solvent in this reaction is a mixture of dichloromethane and diethyl ester.

The compound of formula XXI is converted to a compound of formula XXII by treating the compound of formula XXI with an oxidizing agent. Any conventional'oxidizing agent capable of oxidizing an allylic alcohol to an aldehyde can be utilized in this reaction. The preferred oxidizing agents are silver salts such as silver carbonate, manganese dioxide. Jones Reagent, etc. Any of the conditions conventionally utilized with these reducing agents can be utilized in connection with the reaction of step (m).

The compound of formula III can be obtained by treating the compound of formula XXII with either a phosphorane of the formula:

wherein R-,, R and R are aryl; and R is as above; or a phosphonate of the formula:

wherein R and R are aryloxy or lower alkoxy and R is as above The reaction of a phosphorane of formula XXV with the compound of formula XXII, can, if desired, be carried, be carried out in the presence of an organic solvent. In carrying out this reaction, any conventional organic solvent can be utilized. Among the conventional organic solvents which can be utilized in accordance with this invention are included benzene, toluene, ethylalcohol. N,N-dimethylformamide, 1,2-dimethoxyethane and dioxane. In carrying out this reaction, temperature and pressure are not critical, and this reaction can be carried out at from about 0 to about 50C. and at atmospheric pressure.

The phosphoranes of formula XXV above can be prepared by known procedures from the corresponding phosphonium salts. In accordance with this invention, R R and R can be an aryl group. The aryl groups which may form the substituent designated by R R and R include mononuclear aryl groups such as phenyl or substituent phenyl such as tolyl, xylyl, mesityl, 4- methoxyphenyl, etc. The aryl substituent can be a poly nuclear aryl group such as naphthyl, anthryl, phenanthryl, etc.

The reaction between the phosphonate of formula XXVI and the compound of formula XXII can be carried out by first providing a solution of an alkali metal base and the phosphonate of formula XXVI in an inert organic solvent and then adding the compound of formula XXII to this reaction mixture. In carrying out this reaction, any conventional alkali metal base can be utilized, such as the alkali metal hydrides such as sodium hydride and alkyl lithium; alkali metal lower alkoxides such as sodium methoxide and sodium ethoxide; and the alkali metal amide bases such as sodamide, potassium amide, as well as other alkali metal lower alkyl amides. In carrying out this reaction, any conventional inert organic solvent can be utilized such as benzene, toluene, N,N-dimethylformamide, tetrahydrofuran, dioxane, 1,2-dimethoxyethane. In carrying out this reaction, a temperature of from 0C. to 30C. may be utilized.

The phosphonate of formula XXVI can be substituted by alkoxy or aryloxy groups. As with R R and R in the phosphorane of formula XXV, the aryl groups denoted by R and R in the phosphonate of formula XVI can be mononuclear or polynuclear aryl groups which can be substituted or unsubstituted. When the compound of formula XXVI is substituted by alkoxy groups, it is generally preferred to utilize alkoxy groups containing from 1 to 4 carbon atoms such as methoxy, ethoxy and isopropyl. Among the aryloxy groups, phenoxy groups which are singly or multiply substituted with an alkyl, nitrogen, halogen, lower alkoxy or dialkylamino groups are generally preferred.

In the compounds of formulae XXV and XXVI, R can be aryl, aralkyl or alkyl. The alkyl group includes both lower alkyl groups containing from 2 to 6 carbon atoms and higher alkyl groups containing from 7 to 18 carbon atoms. Among the preferred lower alkyl groups are ethyl, propyl, isopropyl, pentyl, butyl, etc. Among the higher alkyl groups are hexadecyl, octadecyl, decyl, tetradecyl, pentadecyl, octyl, etc. The R, group utilized in the compound of formula XXV and formula XXVI is converted through to the corresponding groups in the compound of formula I and formula III above.

The stereoconfiguration at the 910 double bond in the compound of formula III dpends upon the configuration about the double bond in the 2-3 position in the compound of formula XX. Therefore, if the 2-3 double bond in the compound of formula XX is a trans double bond, the configuration about the double bond in the 9-10 position of formula III will be a trans double bond. On the other hand, if the double bond in the 2-3 position in the compound of formula XX is a cis double bond, the configuration about the 9-10 double bond in the compound of formula III will be a cis configuration. On the other hand, if the compound of formula XX contains a mixture of cis and trans isomers, a compound of formula III which is produced thereby is a mixture of cis/trans isomers.

I 21 The compound of formula I where R is -CI-IO is vitamin A aldehyde. Vitamin A aldehyde can be prepared from the compound V where R,". is hydrogen via an intermediate of the formula:

1 CH3 cs /l\/CHO In converting the compound of formula V where R," is hydrogen to the compound of formula XIX, the compound of formula III is treated with a selective oxidizing agent such as manganese dioxide, silver carbonate or nickel peroxide. Any of the conditions conventional in utilizing these oxidizing agents can be utilized in carrying out this conversion.

The compound of formula XIX can be converted to vitamin A aldehyde by treating with a dehydrating agent as described in connection with reaction step (d) hereinabove. However, it may be best before carrying out reaction step (d) to protect the aldehyde group via an acetal derivative and to convert the free hydroxy groups to a leaving group. Hence, a compound of the formula:

CH3 CH3 CH=R M/K/ 29 wherein -OR is as above; and R is oxo or an acetalized oxo group.

In fonning the compound of formula XIX where OR;, is a leaving group, the same leaving groups and the same manner of formation described in connection with the formation of compounds of the formula VI can be used. In forming the acetal of formula XIX, any conventional method of acetalizing an oxo groups to be drilled. the acetal is generally formed by reaction with a lower alkane which contains from 2 to 6 carbon atoms to yield a lower alkylene dioxy at the 15 position. Any conventional acetal protecting group can be utilized to protect the oxo group in the compound of 50 formula XIX, with the lower alkylene dioxy groups, i.e.,

wherein R is an acetalized oxo group. The compound of formula XX can be converted to vitamin A aldehyde by any conventional means of hydro-, lyzing an acetal group.

I The following examples are illustrative but not limitative of the invention. In the examples, all temperatures are in degrees centigrade.

EXAMPLE 1 1 5 Transl-hydroxy-3-methyl-5-( l-hydroxy-2,2,6-trimethylcyclohexyl )-pent-2-en-4-yno tated. Sodium sulfate was added the suspension was filtered, and the filtrate concentrated to give a crude yellow oil which was dissolved in diethyl ether, washed with sodium bicarbonate and water, and dried. Evaporation of the ether gave a yellow oil which precipitated 3.2 g. of transl-hydroxy-3-methyl-5-( l-hydroxy-2,2,6- trimethylcyclohexyl)-pent-2-en-4-yne as a white crystalline product upon trituration with hexane.

EXAMPLE 2 3-Methyl-5-( l-hydroxy-2,2,6-trimethylcyclohexyl pent-2-en-4-yn- 1 -al The diol (6.0 g.), trans-1-hydroxy-3-methyl-5-( lhydroxy-2,2,6-trimethylcyclohexyl)-pent-2-en-4-yne, was stirred at room temperature in 400 ml. of dichloromethane with 30 g. of manganese dioxide for 1% hours. Filtration and evaporation of the solvent afforded 3- methyl-5-( 1-hydroxy-2,2,6-trimethylcyclohexyl)-pent- Z-en-4-yn-l-al.

UV in isopropanol, A 287 ,u..

' EXAMPLE 3 Ethyl-3 ,7-dimethyl-9-( l-hydroxy-2,2 ,6-trimethylcyclohexyl)-nona-2,4-trans, 6-trans-trien-8-ynoate A solution of 7.45 g. of ethyl-3-diethylphosphonosenocioate in '30 ml. of tetrahydrofuran was added to a suspension of sodium hydride dispersion (1.26 g., 59.2% by weight NaI-I) in 60 ml. of tetrahydrofuran at C. After the addition, the mixture was stirred for 1 hour and a solution of the aldehyde, 3- methyl--( 1hydroxy-Z,2,6-trimethylcyclohexyl )-pent- 2-en-4-yn-1-al, in 30 ml. of tetrahydrofuran was added at 0C. The solution was stirred at room temperature for 2 hours and then poured into ice water. The organic layer was washed with brine, dried and concentrated to afford the crude ester, ethyl 3,7-dimethyl-9-( 1- hydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4-trans,6- trans-trien-8-ynoate. This crudeester was chromatographed on activity III alumina to give pure ethyl 3,7- dimethyl-9-( 1hydroxy-Z,2,6-trimethylcyclohexyl nona-2,4-trans,6-trans-trien-8-ynoate.

UV in isopropanol, A 332 p. (6 40,820).

IR (film), 11 350, 2710 cm EXAMPLE 4 Ethyl 3 ,7-dimethyl-8-keto-9-( 2 2,6-trimethylcyclohexen-1- yl)nona-2,4-trans,6-transtrienoate EXAMPLE 5 I Ethyl 3,7-dimethyl-8-hydroxy-9-(2,2,6-trimethylcyclohexenl-yl )-nona-2,4-trans,6-trans-trie noate The keto ester (2.2 g.), ethyl 3,7-dimethyl-8-keto-9- (2,2,6-trimethylcyclohexen-1-yl)-nona-2,4-trans,6- trans-trienoate, in 100 ml. of ethanol was stirred for 72 hours with 0.6 g. of sodium borohydride. -Water was added and the solution concentrated and the residue extracted with diethyl ether. The extracts were washed with water, dried, and concentrated to give ethyl 3,7- dimethyl-8-hydroxy-9-( 2,2,6-trimethylcyclohexen- 1- yl)-nona-2,4-trans,6-trans-trienoate.

UV in isopropanol, A 312-3 p. '(e 26,500

EXAMPLE 6 Vitamin A acid ethyl ester The hydroxy ester (0.35 g.), ethyl 3,7-dimethyl-8- hydroxy-9-(2,6,6-trimethylcyclohexen-1-yl)-nona-2,4- trans,6-trans-trienoate, was dissolved in 1 ml. of dichloromethane and 0.16 ml. of pyridine and the solution was cooled to 5C. Acetyl chloride (0.1 g. in 1 ml. of dichloromethane was added and the mixture was stirred for 30 minutes at -5C. Water was added and the organic phase was washed with dilute sulfuric acid, sodium bicarbonate, and water. Retreatment as described gave a solution of the 8-acetoxy derivative of 24 the hydroxy ester, i.e., ethyl-3,7-dimethyl-8-acetoxy-9- (2,6,6-trimethylcyclohexen- 1-y1)-nona-2,4-trans,6- trans-trienoate. (In/ (film) 1735 cm). The solution was cooled to 50C. and stirred vigorously during the rapid addition of 0.165 ml. of precooled 62% by weight aqueous hydrobromic acid (20C.). The mixture was stirred 15 minutes at 50C. and ice water and sodium bicarbonate were added. The dichloromethane solution was washed with water, dried, and concentrated to give vitamin A acid ethyl ester.

UV in isopropanol, A 352 p. (e 34,710).

Ir (film), A 1705 cm EXAMPLE 7 1l-Iydroxy-3,7-dimethyl-9-( lhydroxy-3,2,6-trimethylcyclohexyl)-nona-2,4,6-trans-trien-8-yne The hydroxy ester (0.5 g.), ethyl 3,7-dimethyl-9-(1- hydroxy-2,2,6-trimethylcyclohexy1)-nona-2,4,6-transtrien-8-ynoate, in 18 ml. of anhydrous diethyl ether was added to a suspension of 0.88 g. of lithium aluminum hydride in 18 ml. of diethyl ether at C. The mixture was stirred for 1% hours and then decomposed with saturated aqueous sodium sulfate solution. The mixture was filtered and the ether evaporated to give 1hydroxy-3,7-dimethyl-9-( 1-hydroxy-2,2,6-trimethylcyclohexyl)nona-2,4,6-trans-trien-8-yne.

UV in ethanol, A 303 ,u (e =36,535).

EXAMPLE 8 1Acetoxy-3,7-dimethyl-9-( 1-hydroxy-2,2,6-trimethylcyclohexyl )nona-2,4,6-trans-trien-8-yne Acetic anhydride (0.2 ml.) was added to a solution of 0.15 g. of the diol, 1hydroxy-3,7-dimethyl-9-( lhydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4,6-transtrien-8-yne in 5 ml. of pyridine. The solution was heated to 5060C for 1% hours and poured into ice water and extracted with diethyl ether. The extracts were washed with sodium bicarbonate, saturated aqueous cupric sulfate, and brine and dried to give 1- acetoxy-3 ,7-dimethyl-9-( 1-hydroxy-2,2,6-trimethylcyclohexyl)-nona 2,4,6-trans-trien-8-yns.

UV-in isopropanol, A 305 1.1..

EXAMPLE I 9 1-Acetoxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1yl)-nona-2,4,6-trans-triene triene.

UV in ethanol, A 313 p. (e 26,005).

EXAMPLE 1 0 1-Acetoxy-3 ,7-dimethyl-9-( l-hydroxy-2,2,6-trimethylcycl ehexyl )nona-2,4-trans,6-cis-trien-6-yne A solution of 11.78 g. of the diol 7-hydroxy-3,7- dimethyl-9-( lhydroxy-2,2,6-trimethylcyclohexyl)- 25 nona-1,3,5-trien-8-yne, in 33 ml. of glacial acetic acid was warmed to 40C for 2 hours. The reaction mixture was poured into 300 m1. of ice water and extracted with diethyl ether. The extracts were washed with brine, sodium bicarbonate, and brine and dried. Evaporation of the solvent gave 1-acetoxy-3,7-dimethy1-9-(1- hydroxy-2,2,6-trimethy1cyclohexyl)-nona-2,4-trans,6- cis-trien-8-yne.

UV in ethanol, A 302 11..

EXAMPLE 1 1 3-Hydroxy-3,7-dimethyl-nona-4,6,8-trien- 1 -yne A solution of ethyl bromide (5.45 g.) in tetrahydrofuran was added to a suspension of magnesium (1.20 g.) in tetrahydrofuran and the mixture was refluxed for 30 minutes. Acetylene was bubbled into the solution for 2 hours at room temperature and a solution of 6-methy1- octa-3,5,7'trien-2-one (1.80 g.) in tetrahydrofuran was added. The mixture was stirred at room temperature for 1% hours and poured into saturated ammonium chloride solution. The organic layer was washed with brine and dried. Evaporation of the solvent gave 3- hydroxy-3 ,7-dimethyl-nona-4,6,8-trien-1 -yne which was chromatographed on activity 111 allumina to give of pure 3-hydroxy-3 ,7-dimethyl-nona-4,6,8-trien- 1 -yne.

UV in isopropanol, A 267 y. (e 30,225).

EXAMPLE 12 Solution T organic phase was washed with brine dried and concentrated to give 7-hydroxy-3,7-dimethy1-9-( 1-hydroxy-2,2,6-trimethylcyc1ohexyl)-nona- 1,3,5-tr1en-8-yne which was chromatographed on activity III alumina to give pure 7-hydroxy-3,7-dimethyl 9- 1-hydroxy-2,2,6-trimcthylcyclohexyl)-nona-1 ,3,5- tnen-S-yne. 1

UV in isopropanol, Ami; 268-9 ,u.(e= 30,535)

EXAMPLE 13 1-Acetoxy-3 ,7-dimethyl-9-( -hydroxy-2,2,6 trimethylcyclohexyl)-nona-2,4-trans,6:cis-trien-8-yne A solution of 1.33 g. of the diol, 7-hydroxy-3,7- d1methy1-9-( 1 -hydroxy-2,2 ,-trimethylcyclohexyl nona-l,3,5-trien-8-yne, 1.33 g. of glacial acetic acid, and 8 m1. of. benzene was refluxed under argon for 4 hours. The solution was poured into water and extracted with diethylether. The extracts were washed with sodium bicarbonate and brine and dried. Evaporatron of the solvents afforded 1-acetoxy-3,7-dimethy1-9- l-hydroxy-2,2,6 trirnethylcyclohexyl)-nona-2,4- trans,6-cis-trien-8-yne.

UV in isopropanol, A =302 ,u. (t= 30,700)

EXAMPLE l4 3 -Hyroxy-3 ,7-dimethyl-9-( 1-hydroxy-2,2,6-trimethylcyc1ohexy1)-nonal ,4 ,6-cis/trans-trien-8-yne To a stirred solution of vinylmagnesium chloride (6.5 ml. 3.9M) in 25 ml of tetrahydrofuran was added 2.0 g

of the ketone, 2-keto-6-methyl-8-( l-hydroxy-2,2,6- trimethylcyclohexyl)octa-3, 5-cis/trans-dien-7-yne, in 45 ml of tetrahydrofuran. The mixture was refluxed for 1 hour and saturated aqueous magnesium sulfate was added. The mixture was filtered and the filtrate concentrated to afford 3-hydroxy-3,7-dimethyl-9-(1- hydroxy -2,2 ,6-trimethy1cy clohexyl )-nona- 1 ,4,6-cis/- trans-trien-S-yne. This product was chromatographed on activity III alumina to afford pure product.

UV in isopropanol A "m 270 mu (e 23,510)

Ir (film), 11 3450 cm"? EXAMPLE 15 1-Acetoxy-3 ,7-dimethyl-9-( l-hydroxy-2 ,2,6-trimethy1- cyclohexyl )-nona-2,4,6-cis/trans-trien-8-yne.

The diol (0.59 g.), 3-hydroxy-3,7-dimethyl-9-(1- hydroxy-Z,2,6-trimethylcyclohexyl)-nona-1,4,6-cis/- trans-trien-8-yne, was heated at 40C for 1 hour with 5 m1. of glacial acetic acid. The mixture was poured onto ice water, extracted with diethyl ether, and the extracts were washed with sodium bicarbonate and brine and dried. Removal of the solvent afforded l-acetoxy-3,7- dimethy1-9-( 1 -hydroxy-2,2,6-trimethy1cyclohexy1)- nona-2,4,6-cis/trans-trien-8-yne.

UV in isopropanol )t 303 m ,u.

EXAMPLE l6 1-Acetoxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclo'hexenel-yl)-nona-2,4,6-triene By the procedure of Example 16, asolution of 1.0 g. of l-acetoxy-3,7-dimethyl-9-( l-hydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4,6-cis-trien-8-yn and 0.2 g. of tris(triphenylsily1) vanadate in xylene was heated to refiux for two hours to give 1-acetoxy-3,7-dimethyl-8- keto-9-( 2 ,6,6-trimethylcyclohexenl -yl )-nona-2,4,6- cis/trans-triene.

UV in isopropanol: 1:1 ratio of A 302 mp. (starting material) and A 310 mu.

EXAMPLE I 1 8 By the procedure of Example 16, a solution of 1.0 g. of 1-acetoxy-3,7-dimethyl-9-(2,2,6-trimethylcyclohexyl)-nona-2,4,6-cis-trien-8-yne, 0.3 g. of tris(triphenylsilyl) vanadate, 0.09 g. of triphenylsilanol, and 0.015 g. of benzoic acid was refluxed in 15 ml. of mesitylene for 1% hours. Isolation of the product as described above gave 1.2 g. of crude oil which afforded pure l-acetoxy- 3 7-dimet hy1-8-keto-9-( 1 -hydroxy-2 ,6 ,6-trimethylcyclohexenl -y1)-nona-2,4,6-cis/trans-triene after chromatography on deactivated silica gel.

UV in isopropanol, A 310 mu.

EXAMPLE 19 A solution of 1.30 g. of 1-acetoxy-3,7-dimethyl-9- hydroxy-2,2,6-trimethylcyc1ohexyl)-nona-2,4,6-trans- 27 trien-8-yne, 0.47 g. of tris (triphenylsilyl) vanadate, 0.118 g. of triphenylsilanol, 0.025 g. of benzoic acid, and 0.005 g. of hydroquinone was refluxed in 25 ml. of xylene for 2 hours. Isolation of the crude product af' forded 1.25 g. of crude oil which was chromatographed as described in Example 15 to afford 1-acetoxy-3,7- dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1- yl)nona-2,4,6-trans-triene.

UV in isopropanol, k 31 13l2 mu.

EXAMPLE 20 EXAMPLE 21 Isomerization of l-acetoxy-3 ,7-dimethyl-8 -keto9-( 2,6 ,6-trimethylcyclohexenl -yl)-nona-2,4,6 triene A solution of 78 mg. of the ketoacetate, l-acetoxy- 3 ,7-dimethyl-8-keto-9-( 2,6 ,6-trimethylcyclohexenlyl)-nona-2,4,6-cis/trans-triene (mainly having a cis configuration at the 6,7-double bond), in 0.5 ml. of glacial acetic acid was allowed to stand at room temperature for 20 hours. The solution was poured into water and extracted with diethyl ether. The combined extracts were washed successively with sodium bicarbonate and brine and dried. Removal of the solvent afforded the compound 1-acetoxy-3,7-dimethyl-8- keto-9-( 2,6,6-trimethylcyclohexenl-yl )-nona2,4,6- triene which was reduced in the cis configuration about the 6,7-double bond.

NMr: 8 TMS (C-9 methylene) =3.25 (6-cis) and 3.42 ppm (6-trans).

EXAMPLE 22 A solution of 4.0 g. of the acetoxy ketone, l-acetoxy- 3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1- yl)-nona-2,4-trans, 6-cis/trans-triene, and 26.5 g. of piperidine acetate in 400 ml. of benzene was refluxed for 90 hours under argon. Water and diethyl ether were added and the mixture was extracted with diethyl ether. The extracts were washed with 10% by weight aqueous HCl, sodium bicarbonate, and brine and dried. Removal of the solvent gave 4.0 g. of crude product which was chromatographed on silica gel to give the all trans acetoxy ketone.

UV in isopropanol, A 310 my. (6 32,640).

1r: A (film) 1735, 1660, and 1265 cm.

Nmr: 8 TMS (C-9 methylene) 3.42 ppm.

EXAMPLE 23 The following isomerizations of the acetoxy ketone of Example 21 were carried out. In this example, the acetoxy ketone was a -cis/trans isomeric mixture. In the isomerized product there was a substantial increase in the trans configuration about the 7 double bond. In this example, the steps of extraction and isomerization were carried out in the same manner as in Example 21.

a. Starting with 0.12 g. acetoxy ketone (6-cis/trans),

0.093 g. tetramethylammonium acetate, and refluxed in acetone 20 hours.

b. Starting with 0.12 g. acetoxy ketone (6-cis/trans),

0.0193 g. tetramethylammonium acetate, and refluxed in diethyl ketone 20 hours.

0. Starting with 0.1 15 g. acetoxy ketone (6-cis/trans), 0.076 g. diazabicyclo [2.2.2] octane, and refluxed 5 hours in diethyl ketone.

d. Starting with 0.06 acetoxy ketone (6-cis/trans),

1.0 ml. pyridine and heated at reflux for 7 hours.

e. Starting with 0.10 g. acetoxy ketone (6-cis/trans), 1.5 ml. pyridine and heated to reflux for 105 hours.

EXAMPLE 24 All trans-1 ,8 -dihydroxy-3,7-dimethyl-9-( 2,6,6-trimethylcyclohexen-1-yl)-nona-2,4,6-triene 1.765 g. of the keto acetate, all trans-l-acetoxy-3,7- dimethy1-8-keto-9-(2,6,-trimethylcyclohexen- 1 -yl nona-2,4,6-triene in ml. of ethanol was stirred for hours with 0.97 g. of sodium borohydride. Water was added to decompose the excess hydride and the mixture was filtered. The filtrate was concentrated and redissolved in diethyl ether. The ether solution was washed with brine and dried. The solvent was removed to give all-trans-l,8-dihydroxy-3,7-dimethyl-9-(2,6,6- trimethylcyclohexen-1-yl)-nona-2,4,6-triene.

UV in isopropanol A 280 mu.

EXAMPLE 25 All trans-1,8-diacetoxy-3,7-dimethyl-9-(2,6,6-trimethylcyclohexen-1-yl)-nona-2,4,6-triene A solution of 0.9 g. of the diol, all trans-1,8-dihydroxy-3 ,7 -dimethyl-9-( 2 ,6,6-trimethylcyclohexen- 1 yl)-nona-2,4,6-triene in 20 ml. of pypridine was stirred at room temperature with 1 ml. of acetic anhydride for 18 hours and the mixture was poured into ice water and diethyl ether. The organic layer was washed with sodium bicarbonate, saturated aqueous cupric sulfate, and brine and dried. Evaporation of the solvent gave 0.85 g. of all trans-1,8-diacetoxy-3,7-dimethyl-9- (2,6,6-trimethylcyclohexen-1-yl)-nona-2,4,6-triene.

UV in isopropanol A 280 my Ir (film) 11 1730 and 1230 cm.

EXAMPLE 26 Vitamin A acetate A solution of 0.445 g. of the diacetate, all-trans-1,8- diacetoxy-3 ,7-dimethyl-9-( 2,6,6-trimethylcyclohexen- 1-yl)-nona-2,4,6-triene, in 10 ml. of dichloromethane was stirred at -50C. and 1.0 ml. of 62% by weight aqueous hydrobromic acid (20C) was added. The mixture was stirred at 50C. for 7 minutes and then 10 ml. of ice water, 10 ml. of dichloromethane and a solution of 1.7 g. of sodium carbonate in 10 ml. of water was added. The mixture was stirred in an ice bath for 2% hours and the organic layer was washed with brine and dried. Evaporation of the solvent afforded 0.4 g. of crude product which was purified by chromatography on silica gel containing 20% sodium acetate to give 0.155 g. of all trans vitaman A acetate.

UV in isopropanol A 327 my. (6 39,000).

EXAMPLE 27 A solution of 0.1 g. of all trans l,8-dihydroxy-3,7- dimethy1-9-( 2,6,6-trimethylcyclohexen- 1 -yl )-nona- 2,4,6-triene was oxidized with 0.5 g. of activated manganese dioxide in ml. of dichloromethane to produce all trans 3,7-dimethyl-8-hydroxy-9-(2,6,6-trimethylcyclohexen- 1 -yl )-nona-2,4,6-trien- 1 -a1.

EXAMPLE 28 To a solution of 200 mg. of phosphorous oxychloride in ml. of pyridine was added 300 mg. of the hydroxyaldehyde, all tran 3,7-dimethyl-8-hydroxy-9-(2,6,6- trimethylcyclohexen- 1 -yl )-nona-2,4,6-trien- 1 -al, in 2 ml. of pyridine. The mixture was stirred at room temperature for 3 hours, poured into ice water, and extracted with diethyl ether. The extracts were washed with saturated aqueous sodium bicarbonate solution, saturated aqueous cupric sulfate, and brine, and dried. Evaporation of the solvent afforded vitamin A aldehyde.

EXAMPLE 29 EXAMPLE 30 By the procedure of Example 29, a solution of 0.160 g. of 1-acetoxy-3,7-dimethy1-9-(1-hydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4-trans-6-cis-trien-8-yne in 1.0 ml. of toluene containing 0.004 g. of hydroquinone was heated to 8082C. for one hour with 0.040 g. of crude tris-(3,5-dinitrophenylsilyl)vanadate. The solution was diluted with hexane and chilled. The catalyst was removed by filtration and the filtrate concentrated to give 0.1 10 g. of l-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6- trimethylcyclohexenl yl )-nona-2,4,6-triene and 1- acetoxy-3,7-dimethyl-8-keto-9-(2,2,6-trimethylcyclohexylidenyl )-nona-2,4,6-triene.

EXAMPLE 31 A solution of 0.11 g. of the mixture produced in Example 30 in 1 ml. of toluene was added to a mixture of 0.40 g. of piperidine and 0.144 g. of glacial acetic acid in 4 ml. of toluene and was refluxed for 8 hours. Themixture was diluted with diethyl ether, washed with water, sodium bicarbonate solution, 2N hydrochloric acid, and brine and dried. Evaporation of the organic solution alforded a mixture of l-acetoxy-3,7- dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-y1)- nona 2,4,6-triene in which the amount of the 6-cis isomer was reduced and l-acetoxy-3,7-dimethyl-8- 30 keto-9-(2,2,-trimethylcyclohexylidenyl )-nona-2,4,6- triene.

EXAMPLE 32 By the method of Example 24, to a solution of 0.10 g. of the mixture produced in Example 31, in 10 ml. of ethanol is added 0.25 g. of sodium borohydride. After stirring at room temperature for hours, 'the mixture is poured into ice water and 0.2N hydrochloric acid and extracted with diethyl ether. The extracts are washed with aqueous sodium bicarbonate and brine and dried. Evaporation of the solvent affords a mixture of the diols 1,8-dihydroxy-3,7-dimethyl-9-(2,6,6-trimethylcyclohcxen-1-yl)-nona-2,4-trans,-6-trans-triene and l ,8-dihydroxy-3,7-dimethyl-9-( 2,2,6-trimethylcyclohexylidenyl )-nona-2,4,6-triene.

EXAMPLE 33 By the method of Example 25, the mixture of diols from Example 32 (0.08 g.) is acetylated using 2.0 ml. of pyridine and 0.2 ml. of acetic anhydride. The crude product is isolated as in Example 25 giving a mixture of diacetates, l,8-diacetoxy-3,7-dimethyl-9-( 2,6,6-trimethylcyclo hexenl -yl )-nona-2,4-trans,6-trans-triene and l ,8-diacetoxy-3,7-dimethy1-9-( 2,2,6-trimethylcyclohexylidenyl)-nona-2,4,6-triene.

EXAMPLE 34 By the method of Example 26, a solution of 0.82 g. of the diacetoxy compounds produced in Example 33 is treated in 2 ml. of dichloromethane at 50C. with 0.2

ml. of 62% by weight aqueous hydrobromic acid. lsolation as described in Example 26 affords vitamin A acetate.

EXAMPLE 35 To a solution of 0.038 of perfluorotriphenylsilanol was added 0.48 ml. of 1.26% by weight xylene solution of tri n-propyl vanadate. To this solution was added a solution of l-acetoxy-3 ,7-dimethyl-9-( 1-hydroxy-2,2,6- trimethylcyclohexyl)-nona-2,4-trans, 6-cis-trien-8-yne in 0.52 ml. of xylene. The solution was heated at 80C. for 25 minutes and then at C. for 40 minutes. The solution was cooled, diluted with hexane, chilled and filtered to remove the catalyst. The filtrate was washed with water, dried and concentrated to afford 0.143 g. of crude 1-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-yl)-nona-2,4,6-triene.

EXAMPLE 36 A solution of 0.165 g. of l-acetoxy-3,7-dimethyl-9- 1 -hydrox y-2,2,-trimethylcyclohexyl )-nona-2,4- trans,6-cis-trien-8-yne, 0.03 g. of tri-p-chlorophenylsilanol, 0.24 ml. of 1.26% by weight tri-n-propyl vanadate in xylene, 0.003 g. of hydroquinone, and 0.001 g. of hydroquinone in 1.0 ml. of xylene was heated at C. for 40 minutes. Isolation of the product was carried out by first adding hexane. The resulting mixture was chilled and filtered and the filtrate washed with aqueous sodium bicarbonate solution and water and dried. Evaporation of the solvents gave 0.150 g. of l-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethy1cyclohexen- 1 -yl )-nona-2,4,6-triene.

EXAMPLE 37 A solution of 0.186 g. of 1-acetoxy-3,7-dimethy1-9- l-hydroxy-2,2,6-trimethylcyclohexyl )-2,4-trans,6-cistrien-8-yne, 0.038 g. of tris(p-trifluoromethylphenyl)- 31 silanol, 0.0061 g. of tri-n-propyl vanadate, 0.006 g. of hydroquinone and 0.002 g. of benzoic acid in 1 ml. of toluene was heated to 100C. for 35 minutes. Isolation as in Example 36 affords 0.322 g. of a mixture of crude l-acetoxy-3 ,7-dimethyl-8-keto-9-( 2,6,6-trimethylcyclohexenl -yl )-nona-2,4,6-triene and l-acetoxy-3,7- dimethyl-8-keto-9-(2,2,6-trimethylcyclohexylidenyl)- nona-2,4,6-triene.

EXAMPLE 38 EXAMPLE 39 A solution of 0.160 g. of 1-acetoxy-3,7-dimethyl-9- 1-hydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4-trans, 6-cis-trien-8-yne, 0.0225 g. of tri-m-tolysilanol, 0.24 ml. of 1.26% by weight n-propyl vanadate in xylene, 0.003 g. of hydroquinone, and 0.001 g. of benzoic acid in 1 ml. of xylene was refluxed for 50 minutes. Isolation as described in Example 36 affords 0.145 g. of lacetoxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen- 1 -yl )-nona-2,4,6-triene. v

EXAMPLE 40 A solution of 0.181 g. of 1-acetoxy-3,7-dimethyl-9- l-hydroxy-2,2,6-trimethylcyclohexyl )-noria-2,4- trans,6-cis-trien-8-yne, 0.0185 g. of dicyclohexylmethylsilanol, 0.24 ml. of 1.26% by weight tri-n-propyl vanadate in xylene, 0.003 g. of hydroquinone, and 0.001 g. of benzoic acid in 1 ml. of xylene was refluxed for hours. Isolation as described in Example 36 affords 0.167 g. of crude 1-acetoxy-3,7-dimethyl-8-keto- 9-(2,6,6-trimethylcyclohexen-1-yl)-nona-2 ,4,6-triene.

EXAMPLE 41 A solution of 0.482 g. of 1-acetoxy-3,7-dimethyl-9- l-hydroxy-2,2,6-trimethylcyclohexyl )-nona-2-4- trans,6-cis-trien-8-yne, 0.124 g. of tri-l-naphthylsilanol, 0.018 g. of tri-n-propyl vanadate, 0.007 g. of hydroquinone and 0.003 g. of benzoic acid in 2.3 ml. of xylene was refluxed for one hour. An aliquotwas removed and the product examined by UV and nmr. The UV had a broad maximum at )t 296-318 ,u., and the nmr had several additional strong resonances attributable to the initially formed 1-acetoxy-3,7-dimethyl-8-keto-9-( 2,2,6-trimethy lcyclohexylidenyl )-nona- 2,4,6-triene. The major portion of the reaction mixture was refluxed a total of 2.25 hours and the product isolated as described in Example 36 giving a total of 0.434 g. of 1-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6- trimethylcyclohexenl -yl )-nona-2,4,6-triene having a UV in isopropanol at A 310 1.4.(6 13,855). The additional resonances due to the initially formed alpha,beta-unsaturated ketone seen in the aliquot were weak or non-existent.

EXAMPLE 42 A solution of 0.355 g. of l-acetoxy-3,7-dimethyl-9- l-hydroxy-2,2,6-trimethylcyclohexyl )-nona-2,4- trans,6-cis-trien-8-yne, 0.054 g. of tri-ptolylsilanol, 0.012 g. of tri-n-propyl vanadate, 0.006 g. of hydroquinone, and 0.002 g. of benzoic acid in 1.75 ml. of xylene was refluxed for 2.75 hours. Isolation as described in Example 36 afforded 0.36 g. of crude l-acetoxy-3,7- dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-yl)- nona-2,4,6-triene.

EXAMPLE 43 A solution of 0.340 g. of l-acetoxy-3,7-dimethyl-9- 1-hydr0xy-2,2,6-trimethylcyclohexyl)-nona-2,4- trans,6-cis-trien-8-yne, 0.053 g. of tricyclohexylsilanol, 0.012 g. of tri-n-propyl vanadate, 0.006 g. of hydroquinone and 0.002 g. of benzoic acid in 1.75 ml. of xylene was refluxed for 13 hours. Isolation as described in Example 36 affords 0.269 g. of crude l-acetoxy-3,7- dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-yl)- nona-2,4,6-triene.

EXAMPLE 44 v A solution of 0.347 g. of 1-acetoxy-3,7-dimethyl-9- l-hydrox y-2,2,6-trimethylcyclohexyl )-nona-2,4- trans,6-cis-trien-8-yne, 0.042 g. of diphenylmethylsilanol, 0.012 g. of tri-n-propyl vanadate, 0.006 g. of hydroquinone, and 0.003 g. of benzoic acid in 1.75 ml. of xylene was refluxed for 4 hours. Isolation of the product as described in Example 36 affords 0.336 g. of crude 1-acetoxy-3,7-dimethyl-8-keto-9 (2,6,6-trimethylcyclohexen- 1 -yl )-nona-2,4,6-triene.

EXAMPLE 45 A solution of 0.495 g. of l-acetoxy-3,7-dimethyl-9- 1-hydroxy-2,2,6-trimethylcyclohexyl )-nona-2,4- trans,6-cis-trien-8-yne, 0.0674 g. of tris(trimethylsilyl vanadate, and 0.011 g. of benzoic acid in 2.5 ml. of xylene was refluxed for 3 hours. The mixture was cooled, diluted with diethyl ether, washed with aqueous sodium bicarbonate and water and dried. Evaporation of the solvents affords 0.470 g. of crude 1-acetoxy-3,7- dimethyl- 8-keto-9-( 2 ,6, 6-trimethylcyclohexen-1-yl)- nona-2,4,6-triene.

EXAMPLE 46 A solution of 0.324 g. of 1-acetoxy-3,7-dimethyl-9- l-hydroxy-2,2,6-trimethylcyclohexyl )-nona-2,4- trans,6-cis-trien-8-yne, 0.063 g. of tri-pfluorophenylsilanol, 0.012 g. of tri-n-propyl vanadate, 0.006 g. of hydroquinone, and 0.002 g. of benzoic acid in 1.75 ml. of xylene was heated to C. for one hour. Isolation of the product as described in Example 36 gave 0.312 g. of crude l-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6- trimethylcyclohexen-1-yl-)-nona-2,4,6-triene.

EXAMPLE 47 A solution of 0.371 g. of 1-acetoxy-3,7-dimethyl-9- 1-hydroxy-2,2,6-trimethylcyclohexyl )-nona-2,4- trans,6-cis-trien-8-yne, 0.107 g. of tri-p-bromophenylsilanol, 0.012 g. of tri-n-propyl vanadate, 0.006 g. of hydroquinone, and 0.002 g. of benzoic acid in 1.75 ml. of toluene was refluxed for 35 minutes. Isolation as in Example 36 affords 0.293 g. of a mixture of crude l-acetoxy-3 ,7-dimethyl-8-keto-9-( 2,6,6-trimethylcyclohexen- 1 -yl )-nona-2,4,6-triene and l-acetoxy-3 ,7-

33 dimethyl-8-keto-9-(2,2,6-trimethylcyclohexylidenyl)- nona-2,4,6-triene.

EXAMPLE 48 g Preparation of tris( 3,5-dinitrophenyl )sil'anol To a stirred mixture of 15.41 g. of nitronium tetrafluoroborate and 95 ml. of tetramethylene sulfone was added at 15-25C. over 20 minutes 10.8 g. of triphenylsilanol. The solution was heated to 35C. for 15 minutes, cooled to 15C. and treated with a second portion of 16.88 g. of nitronium tetrafluoroborate. The temperature was increased to 95C. and the mixture stirred at 95C. for 1 1/3 hour. The mixture was cooled, poured onto ice and saturated aqueous sodium bicarbonate and wasextracted with diethyl ether. The ex-.

tracts were washed with brine, dried, and concentrated to give 20.13 g. of a yellow powder, tris(3,5-dinitrophenyl)silanol.

EXAMPLE 49 Preparation of tris(3,S-dinitrophenylsilyl)vanadate EXAMPLE 50 Preparation of tris( 3-nitrophenyl)silanol To a solution of 1.41 g. of triphenylsilanol in 7 ml. of tetramethylene sulfone at 10C. was added 2.50 g. of nitronium tetrafluoroborate in 30 ml. of tetramethylene sulfone over 30 minutes at l20C. The mixture was stirred at l020C. for 25 minutes, poured into 100 ml. of saturated sodium bicarbonate solution and was extracted with diethyl ether. The extracts were washed with brine, dried, and concentrated to give 1.95 g. of crude tris(3nitrophenyl)silanol..

EXAMPLE 51 Preparation of tris( 3-nitrophenylsilyl)vanadate To a solution of 0.254 g. of tris( 3-nitrophenyl)silanol in ml. of benzene was added 0.055 g. of tri-n-propyl vanadate. The mixture was stirred at 25C. for 10 minutes and then heated to reflux for 40 minutes after which time 7 ml. of the benzene was distilled out. Toluene ml.) was added and 9 ml. distilled out over 30 minutes. The reaction mixture was then diluted with 100 m1. of hexane, chilled overnight, and filtered to afford 0.237 g of tris( 3-nitrophenylsilyl)vanadate.

EXAMPLE 52 This example is directed to the preparation of different catalysts that can be utilized in place to the tris (triphenylsilyl) vanadate in Example 4.

0.5 grams of tri (a,a,a-trifluoro-m-tolyl)-silanol (m.p. 72-73C.) was dissolved in 30 ml. of absolute benzene. To the solution was added, 0.115 grams of tris-(trimethyl-siloxy);vanadium oxide. The mixture was refluxed for one hourby heating to boiling. From 34 the reaction mixture, there was distilled off at atmospheric pressure, 20 ml. of benzene and the trimethyl silanol which formed. Finally after the addition of 20 ml. of toluene, another 20 ml; of a benzene toluene mixture was distilled off at atmospheric pressure. The remaining toluene solution evaporated under reduced pressure at 50C. One obtained tris [tri (a,a,a-trifluoio-m-tolyD-siloxy] vanadium oxide [Molpeak 1504].

By this procedure: Tris-(trimethylsiloxy)-vanadiumoxide and Tris-(a,a,a-trifluor-p-tolyl)-silanol were reacted to form Tris-[tri-(a,a,a-trifluor-p-tolyl)-siloxy]-vanadiumoxide [Molpeak 1504]; Tri-(p-fluorphenyl )-silanol, and tris-(trimethylsiloxy) vanadium oxide; and Triphenylsilanol were reacted in a mole ratio of 1: 1:2

to form (Tri-p-fluorphenyl)-siloxy-bis-(triphenylsiloxy)- vanadiumoxide; mp. 203C; Tris-(trimethylsiloxy)-vanadiumoxide, Tri-(p-fluorphenyl)-silanol, and Triphenylsilanol were reacted in a mole ratio of 1:2:1: to form Bis- [tri-( p-fluorophenyl )-siloxy -triphenylsiloxyvanadiumoxide, [Molpeak 1000]; Tris-(trimethysiloxy )-vanadiumoxide, Tri-( p-bromophenyl)-silanol and Cyclohexanol were reacted in a mole ratio of 1:2:1:

to form Bis-[tri-(p-bromphenyl)-siloxy]-cyclohexyloxyvanadiumoxide. [Molpeak 1184]; Tris-(trimethyl-siloxy)-vanadiumoxide; and Bis-(3- nitro-4-bromphenyl)-(4-bromphenyl)-silanol were reacted to form Trisbis-( 3-nitro-4-bromphenyl 4-bromphenyl siloxy]-vanadiumoxide [Molpeak 600].

EXAMPLE 53 The starting material bis (3-nitro-4-bromophenyl)- silanol for use in Example 52 was prepared as follows:

1 g. of tri-(p-bromophenyl)-silanol was dissolved in sulfolane. To this solution there was added, dropwise at 10C., 98 grams of sodium tetrafluoroborate[- NaO BF in 25 ml. of sulfolane. This addition was carried out in an apparatus which does not allow any water to enter into the reaction mixture. The reaction mixture was stirred for 1 hour at room temperature, after which saturated aqueous sodium bicarbonate solution was added thereto. After this addition, the reaction mixture was extracted with diethyl ether. The ether extract was washed with an aqueous saturated sodium sulfate solution and dried over sodium sulfate and evaporated at room temperature and reduced pressure. The residue was bis-(3-nitro-4bromophenyl)-4- silanol which melted after crystalization from a nitrobenzene-petroleum ether mixture at 21 1C.

EXAMPLE 54 This example is directed to the preparation of different catalysts that can be utilized in place to the tris(triphenylsilyl) vanadate in Example 4. i

1 g. of tri(p-fluorophenyl) silanol was dissolved in 3 ml. of absolute benzene. To this solution, there was added 0.255 ml. of pyridine and 0.173 g. of vanadium oxytrichloride. Care was taken during this addition, to keep out any moisture from the reaction mixture. The

35 36 resulting mixture was first stirred at room temperature CH H and then heated for two hours at reflux conditions. R After this period, the reaction mixture was cooled to 21 10C. whereupon the pyridinium hydrochloride, which precipitated, was filtered off. The filtrate was dried under reduced pressure. The residue which resulted o was tris[tri-(p-fluorophenyl)-siloxy]-vanadium oxide which had a melting point of 147C. upon crystallizawherein 21 is z 1 0f tion from n-heptane. 0 By the above procedure: H vanadium oxytrichloride was reacted with tri(pchlorophenyn'silanol l27 12lC') to R is alkano lcontainin from 2 to 18 carbon atoms produce tris[tri (p-chlorophenyl)-siloxy]vanadium R i 1 f 2 0xide(m p=181C or groy an 1 11s a y lcllontamlng rom to vanadium oxytrichloride was reacted with tri(pi my or y l bromophenyl) Silanol, p lzoolzloc.) to p comprising treating In an mert organic so vent, at a duce M p p y y] empelrature of from 35 v to 200 C, a compound of the oxide (m.p. 175C); and 0mm vanadium oxytrichloride was reacted with tri-4- biphenylyl-silanol (mp. l99200C.) to produce tris[tri-(4-biphenylyl)-siloxy]vanadium oxide. We claim: l. A process for producing an all trans isomer of a compound of the formula:

CH3 CH3 R YK/lk/LK%S 2 0 wherein R is -Cl-l OR or wherein R is as above in the presence of a catalyst of the formula: 0

C-OR,; l i

R, is alkanoyl containing from 2 to 18 carbon atoms, wherein R is alkyl, cycloalkyl, aryl, aryl lower alkyl, or aroyl and R is alkyl, aryl or aralkyl; or cycloalkyl substitued lower alkyl; R is R, or comprising providing a compound of the formula: (R -Si; m is an interger from 1 to 3; and n is an wherein R is as above; and interger from 0 to 2, with the proviso that the sum wherein said compound is a mixture of isomers or in an of m and n is 3.

isomeric form other than the all trans form; and treat- 5. The process of claim 4 wherein said catalyst is ing said compound with an organic amine base or an tris-(triphenyl-siloxy)-vanadium oxide.

organic acid at a temperature of from 20 to 160C. 6. The process of claim 4 wherein treating is carried 2. The process of claim 1 wherein said compound is out in the presence of at least 0.01 mole based upon treated with an organic amine base. the moles of the compound to be treated of a silanol of 3. The process of claim 2 wherein said base is piperithe formula:

dine acetate. 4):x iOH 4. A process for producing a compound of the forwherein R is lower alkyl, cycloalkyl, aryl, aryl lower mula: alkyl, or cycloalkyl substituted alkyl.

7. The process of claim 6 wherein said silanol is triphenyl silanol and said catalyst is tri-(triphenylsiloxy)- vanadium oxide.

8. A compound of the formula:

CH H

wherein R is CH OR, and;

R is alkanoyl containing 2 to 18 carbon atoms or aroyl.

9. The compound of claim 8 wherein said compound is ethyl clohexenl y] )-nona-2,4,6-trienoate.

10. The compound of claim 9 wherein said pound is the all trans isomer.

11. A compound of the formula:

3,7-dimethyl- 8-keto-9-( 2,6;6-trimethylcycompound is the all trans isomer.

l-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6- 

1. A PROCESS FOR PRODUCING AN ALL TRANS ISOMER OF A COMPOUND OF THE FORMULA:
 2. The process of claim 1 wherein said compound is treated with an organic amine base.
 3. The process of claim 2 wherein said base is piperidine acetate.
 4. A PROCESS FOR PRODUCING A COMPOUND OF THE FORMULA:
 5. The process of claim 4 wherein said catalyst is tris-(triphenyl-siloxy)-vanadium oxide.
 6. The process of claim 4 wherein treating is carried out in the presence of at least 0.01 mole % based upon the moles of the compound to be treated of a silanol of the formula: (R4)3-Si-OH wherein R4, is lower alkyl, cycloalkyl, aryl, aryl lower alkyl, or cycloalkyl substituted alkyl.
 7. The process of claim 6 wherein said silanol is triphenyl silanol and said catalyst is tri-(triphenylsiloxy)-vanadium oxide.
 8. A compound of the formula:
 9. The compound of claim 8 wherein said compound is ethyl 3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-yl)-nona-2,4,6-trienoate.
 10. The compound of claim 9 wherein said compound is the all trans isomer.
 11. A compound of the formula:
 12. The compound of claim 11 wherein said compound is 1-acetoxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-yl)-nona-2,4,6 -triene.
 13. The compound of claim 12 wherein said compound is the all trans isomer.
 14. The compound of claim 11 wherein said compound is 1-palmitoyloxy-3,7-dimethyl-8-keto-9-(2,6,6-trimethylcyclohexen-1-yl)-nona -2,4,6-triene.
 15. The compound of claim 14 wherein said compound is the all trans isomer. 